It is conventionally known that a modified polymer is produced by reacting a polymer with a compound having a nitroxide free radical in the molecule stable at room temperature and in the presence of oxygen, an organic peroxide, and a radically polymerizable monomer having a functional group.
For example, Patent Documents 1 and 2, which disclose the inventions filed by the present applicant, disclose a method for producing a modified polymer, the method comprising mixing and reacting a polymer having an isomonoolefin unit (e.g., polyisobutylene, butyl rubber, isobutylene/para-methylstyrene copolymer, halogenated butyl rubber, or a brominated isobutylene/para-methylstyrene copolymer), 2,2,6,6-tetramethyl-1-piperidinyloxy or its derivative (i.e., a nitroxide free radical-containing compound), and an organic peroxide in a non-solvent system in a kneader, and reacting the resulting mixture with a functional group-containing polymerizable monomer comprising an acrylic monomer or an aromatic vinyl monomer to graft the polymer having an isomonoolefin unit with the functional group-containing polymerizable monomer, thereby producing a modified polymer.
According to the descriptions of the Examples of Patent Documents 1 and 2, the graft reactions of the polymer having an isomonoolefin unit with the nitroxide free radical-containing compound and the functional group-containing polymerizable monomer were carried out by kneading for 15 minutes at temperatures of 175° C. and 185° C., respectively.